A simulated tissue structure for practicing surgical techniques is provided. In particular, a realistic organ model or tissue portion for practicing the removal of a tumor or other undesired tissue followed by suturing a remnant defect as part of the same surgical procedure is provided. The simulated tissue structure includes an artificial tumor disposed between layers of elastomeric material and mounted on a simulated organ wall or tissue portion. The simulated tissue structure is modular and interchangeable. At least one of the layers includes a mesh reinforcement. A defect comprising two juxtapositioned surfaces defining a gap between the surfaces is created in the simulated tissue structure and the trainee practices tumor removal and closure of the gap by suturing in a laparoscopic environment.